{"cve":"CVE-2019-18802","nvd":{"published":"2019-12-13T13:15:11.383","modified":"2026-06-17T02:25:21.857","status":"Modified","description":"An issue was discovered in Envoy 1.12.0. An untrusted remote client may send an HTTP header (such as Host) with whitespace after the header content. Envoy will treat \"header-value \" as a different string from \"header-value\" so for example with the Host header \"example.com \" one could bypass \"example.com\" matchers.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","score":9.8},"cwes":[],"references":["http://lists.opensuse.org/opensuse-security-announce/2020-03/msg00034.html","https://blog.envoyproxy.io","https://github.com/envoyproxy/envoy/commits/master","https://github.com/envoyproxy/envoy/security/advisories/GHSA-356m-vhw2-wcm4","https://groups.google.com/forum/#%21forum/envoy-users"],"products":["envoyproxy:envoy"],"source":"nvd","synced_at":"2026-10-19T20:59:27.069234358+00:00"},"epss":{"cve":"CVE-2019-18802","score":0.02457,"percentile":0.8443,"date":"2026-10-31"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}